Selective cyclization of alkynols and alkynylamines catalyzed by potassium tert-butoxide

Potassium tert -butoxide ( t -BuOK) was found to be an effective catalyst for the cyclization of aromatic alkynols and alkynylamines. In the presence of 10 mol % t -BuOK, a range of alkynols were converted to the corresponding exo -cyclic enol ethers as pure Z -stereoisomers with 100% selectivity and moderate to excellent yields. Moreover, the cyclization of alkynylamines was also achieved to afford indoles and isoindolin-1-ones in good yields.